1. Field of the Invention
This invention relates generally to the automatic power release and opening of the closed and latched tailgate of a vehicle. In particular, the invention relates to minimizing, or substantially eliminating, the uneven motion of the tailgate and the significantly audible “pop” or “snap” sound that is emitted when the tailgate is released by the latch preparatory to opening.
2. Description of the Related Art
Many vehicles, particularly sport utility vehicles (SUVs), and more particularly so-called luxury SUVs, employ a power rear tailgate that can be automatically opened and closed with, for example, a system comprising switches capable of initiating an action, microcontrollers capable of receiving signals from the switches, and motors capable of effecting the initiated action, such as closing and latching or unlatching and opening the tailgate, via the microcontrollers. For example, when the tailgate is in an open position and one desires to close and latch it, a switch is first closed to initiate the desired (closing) action. This switch may be located in the passenger compartment within reach of the driver. It may also be contained within a handheld wireless remote control device, usually attached to the vehicle ignition key, carried by the driver. The signal from the switch is then transmitted to motors which effect the closing of the tailgate. In an exemplary system, there are two motors, one that rotates the tailgate between the open and closed position and one that latches and unlatches the tailgate. The tailgate opening and closing means, comprising a tailgate actuator and a tailgate actuator arm, is secured to the body, or frame, of the vehicle and operatively connected to the tailgate. The latching means is also secured to the body of the vehicle and includes a latch which is adapted to engage a catch secured to the tailgate.
Further included is a compressible seal interposed between the tailgate and the tailgate frame and generally attached to the tailgate frame itself. When the tailgate is in the fully-closed position, the seal fills what would otherwise be gaps between the tailgate and the tailgate frame, thus helping to reduce entry of road and other external noise from the passenger compartment, inhibit rattles between the tailgate and the tailgate frame, and keep water, dust, and other unwanted matter from entering the vehicle.
Due to mechanical design considerations, particularly due to the elastic force exerted by the typical compressible seal, the tailgate actuator, or motor, and its associated mechanical system are generally not strong enough to close the tailgate from a nominally-closed position, where the tailgate is resting on a nominally-compressed seal, to a fully-closed position, where the seal is further compressed. When closing the tailgate, the latch actuator and latch system are employed to engage the catch and pull the tailgate into the latched, fully-closed position. Preparatory to opening the tailgate, the latch actuator then causes the latch to disengage from the catch. Unfortunately, this disengaging action, in which the catch slips from the confines of the latch, occurs quite suddenly because the engaged structures are under tension due to the compressed, elastic seal. This tension causes an undesirable loud “pop” or “snap” sound as the compressed seal exerts an opening force on the tailgate. Further, the opening motion of the tailgate appears uneven or abrupt. These events, especially with respect to a luxury vehicle, detract from the refined image such a vehicle should project.
Therefore, there is a need for a vehicle tailgate release and opening system that minimizes or reduces the loud popping sound and the sharp jerking motion currently associated with the opening of powered vehicle tailgates.